1. Field of the Invention
This invention relates to a method for manufacturing an air spoiler for ensuring stability when a car is running at a high speed and particularly to a method for manufacturing a hollow air spoiler.
2. Brief Description of the Prior Art
1 There is a conventional method for manufacturing an air spoiler in which an air spoiler (A) with a hollow interior is formed by blowing, as shown in FIGS. 1, 2 and 3 (rear air spoiler is exemplified).
In this blow molding, large fins are generated from the mating surfaces of a forming metal mold. Also, in the molding process, vacuum drawing is effected from the outer surface of the forming metal mold at the same time the mold is tightened after the parison process is ended in order to charge high pressure air or gas into the parison. Owing to irregular line at the parison time, vacuum drawing and shortage of charging amount of high pressure air, pin holes or the like are generated in the outer surface layer of the forming metal mold. In order to apply a high quality coating to the flush (flat) surface of a finished product, a large number of processes such as a fin finishing process and a sanding process are required.
Also, as a uniform wall thickness is sometime unable to obtain depending on the configuration of a product, the product is manufactured with reference to a wall thickness thicker than necessary. As a result, waste of material occurs. Furthermore, it has such a shortcoming as that a complicated internal configuration required for forming a reinforcement rib and a bearing surface for mounting other parts thereon is unobtainable.
2 There is another conventional method for manufacturing an air spoiler, in which a reinforcement metal piece (a) is provided to the interior as shown in the sectional views of FIGS. 4 and 5, and a soft or hard foam urethane resin is formed into an air spoiler by reaction molding.
According to this urethane reaction molding, since a reinforcement metal piece (a) is provided to the interior, it has such a shortcoming as that the weight becomes heavy. It also has such a shortcoming as that after the reaction molding, a void existing in a molded product causes the outer surface to be swollen when a coating is applied, or a post foaming is taken place when coating of the molded product is being dried and the coating surface of the molded product is swollen. By this, the yield of product of a finished product becomes bad and a finished product of high quality is unobtainable.
3 There is still another conventional method for manufacturing an air spoiler in which a hollow member, as shown in the sectional view of FIG. 6, is comprised of an upper part (1) and a lower part (2), the upper part (1) being formed into a convex shape and the lower part (2) into a concave shape, an adhesive agent (t) is charged into a concave portion (c) of the lower part (2) and then the upper part (1) is united and attached onto the lower part (2). Thereafter, a putty (t') is applied to the entire periphery of a gap portion (c') of the outer surface and then dried and subjected to sanding treatment.
According to this two part attaching method, there are such shortcomings as that a uniform strength is difficult to obtain owing to irregularity of the applying amount of adhesive agent (t) and that since the coating, baking and drying operation are performed after a putty (t') finishing operation was effected to the mating surfaces of the two parts, the putty (t') charging portion is deformed to a concave shape. As a result, the merchandise value with respect to the outer appearance is lowered.
The present invention has been accomplished in order to obviate the problems inherent in the above-mentioned three conventional methods 1, 2 and 3.